Scores of casualties are still in hospitals across London following the explosions, many recovering after surgery.

Doctors worked through the night treating the injured for burns, amputations and multiple body injuries.

Many hospitals called in extra staff as they instigated their emergency plans.

More than 700 people were hurt and 37 died in the four blasts. People worried about relatives or friends are being advised to call 0870 1566 344.

Home Secretary Charles Clarke said he expected the death toll to rise.

"There are a number of people terribly injured in hospital still and we don't know how they're going to survive or not - and so I'm not going to speculate on figures - but I do think it will be higher than 37,"

Whitechapel's Royal London Hospital saw the most casualties with more than 200 people being brought in - of those 26 remained in hospital on Friday, seven in the intensive care unit and 19 on wards.

Senior consultant Laurence Gant said in a statement: "The Royal London Hospital was fully staffed last night. All staff due on duty made their way into work despite transport difficulties.

"We are continuing to treat inpatients from yesterday's incident."

The Royal Free Hospital in north London said 13 were still in hospital, five of whom had undergone surgery. All were in a stable condition, a spokeswoman said.

Some 27 people have been admitted to University College Hospital, four are said to be in a serious condition.

Professor Jim Ryan, a senior A&E consultant who is leading the major incident team, said: "The characteristic injury of a terrorist incident is multiple injuries to multiple body systems, and that is what we have seen."

A dozen people are being treated at Guy's and St Thomas's, near Waterloo.

A spokeswoman said: "Patients are being treated for smoke inhalation, burns and serious limb and chest injuries."

Great Ormond Street Hospital for Children, which set up makeshift facilities under its major incident plan as it does not have an A&E department, treated 22 people - 18 of which stayed overnight.